With 1989’s In the Line of Duty IV, we finally get an entry in the series that offers some continuity - maybe. The first three – 1985’s Yes, Madam!, 1986’s Royal Warriors and 1988’s In the Line of Duty 3 - shared the concept of a young female police officer in Hong Kong but otherwise maintained no real connections from one to another.

With Duty IV, we finally get a link, as the lead character from Duty III carries over to this film – again, maybe.

Does Cynthia Khan play a character with the same name as her Duty III role? Yes.

Does this mean anything in the loosey-goosey world of Hong Kong cinema, one where many actors just use their own names for their characters? Not really, so it remains entirely unclear if Khan portrays the same role in the two films.

Set in Seattle, harbor worker Luk Wan-Ting (Yat Chor Yuen) witnesses murder committed by rogue CIA agents involved with the drug trade. When Luk gets arrested and beaten by a dirty cop to reveal the location of missing film, he escapes and goes on the run.

Hong Kong police officer Rachel Yeung (Cynthia Khan) gets partnered with Seattle cop Donnie Yen (Donnie Yen) to track Luk and take him back into custody. This leads them on a dangerous trip complicated by international skullduggery.

I guess Duty IV technically falls into the “buddy cop” genre, though it makes the mismatched partners more antagonistic than usual. Rachel and Donnie act in much more aggressive ways toward each other than we normally see, a choice that adds edge to the proceedings.

Beyond that minor twist, Duty IV offers a fairly conventional story of a witness who needs to be kept alive by law enforcement. No one should expect a particularly original plot, and as told here, it can become unnecessarily convoluted at times.

Predictable as it might seem, at least the narrative of Duty IV feels more consistent than the plots of the prior movies. Also, even with the surprising level of animosity between them, Khan and Yen make a strong team.

As expected, Duty IV fares best when it engages in action, and it provides arguably the wildest stunts and fights of the four films. We get real bang for the buck from these, as these seem unusually dynamic and inventive.

Even with some flaws, these factors make Duty IV a largely enjoyable flick. It does enough right to easily overcome its drawbacks.

In the Line of Duty IV appears in an aspect ratio of 1.85:1 on this Blu-ray Disc. The prior three films in the “series” looked good and that trend continued with this one.

Sharpness worked well. A smidgen of softness popped up in some wider shots, but the majority of the film felt accurate and well-defined.

I witnessed no issues with jaggies or shimmering, and edge haloes didn’t appear. Grain felt natural, while print flaws were limited to a large but brief streak I saw at one point.

Colors went for a subdued but still largely natural impression. The tones felt well-rendered and full.

Blacks seemed deep and dark, while shadows offered nice clarity and delineation. This turned into another fine transfer.

Whereas the prior three movies in the Duty “franchise” offered audio that varied from flawed to awful, the DTS-HD MA monaural track for Duty IV seemed wholly, perfectly… mediocre. But hey, after the poor quality of the other flicks’ mixes, I’ll take it.

The looped dialogue always sounded artificial, but at least the lines remained intelligible and without substantial edginess. Music demonstrated reasonably good range and clarity.

Effects could appear a bit stiff, but they showed adequate accuracy and presented only a little distortion. Again, nothing here impressed, but the mix seemed competent, a nice step up after the terrible sound of its predecessors.

As we shift to extras, we find two audio commentaries, the first of which comes from Hong Kong film expert Frank Djeng and filmmaker Michael Worth. Both sit together for this running, screen-specific look at cast and crew, stunts and martial arts, sets and locations, genre domains, and some production topics.

Djeng and Worth recorded their track for Duty III, got dinner and came back for Duty IV. Perhaps their sushi meal made them sleepy, as this becomes a largely dull discussion.

Whereas Djeng usually offers rapid-fire notes, he comes through with much less information here, and Worth fails to pick up the slack. A few useful tidbits emerge but in general, we find a less than enthralling chat.

For the second commentary, we hear from Hong Kong film expert Stefan Hammond and actor Michael Wong. They sit together for a running, screen-specific discussion of story/characters, cast and performances, sets and locations, stunts and action, and connected domains.

Recorded for a circa 2001 DVD, this one benefits from the presence of Wong, an actual participant in the shoot. However, don’t expect a lot of insights from him.

Wong tends to toss out minor memories, while Hammond often just narrates the film. While we get a handful of good thoughts, the track feels decidedly mediocre.

An archival Interview with Actor Donnie Yen goes for 20 minutes, 29 seconds. He discusses aspects of Hong Kong cinema as well as some movie-specific thoughts.

Some of Yen’s comments offer useful insights into the martial arts genre. However, he can sometimes do little more than praise the Hong Kong scene, so the chat seems spotty.

In addition to both English and Hong Kong trailers, the disc includes an Export Version of Duty IV. It runs one hour, 35 minutes, 38 seconds and appears to differ from the Hong Kong edition mainly because it adds a brief piece of exposition early in the tale.

Note that this Blu-ray for Duty IV comes as part of a four-movie In the Line of Duty I-IV collection. It also includes 1985’s Yes, Madam!, 1986’s Royal Warriors and 1989’s In the Line of Duty IV.

This means a mix of non-disc-based materials that apply to all four movies. Two double-sided posters emerge. One advertises Royal Warriors on both sides, while the other shows Yes, Madam! on one side and promotes all four films on the other.

A 100-page booklet comes packed with credits, photos, art and a mix of essays/interviews. It acts as a terrific complement to the package.

Arguably the best of the loose franchise to that point, In the Line of Duty IV does not always hit on all cylinders. Still, it brings a stronger story than usual and connects with solid action. The Blu-ray delivers fine visuals, adequate audio and a selection of supplements. This winds up as a pretty exciting cop flick.